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Last modified: June 2010

AHELP for CIAO 4.2


Context: tools


Sets the bad pixel parameters of the ardlib file to the given file


acis_set_ardlib  badpixfile [absolutepath] [ardlibfile] [verbose]


This script tells ardlib to use the specified ACIS bad pixel file. It does this by setting the AXAF_ACIS<n>_BADPIX_FILE parameters in the ardlib parameter file for all the blocks in the input file which match the string "BADPIX<n>". It does not work with HRC bad pixel files.

Each Chandra observation comes with an observation-specific bad pixel file (the *bpix1.fits file in the primary/ directory of the distribution). It is also possible to create a bad pixel file in CIAO, with the "acis_run_hotpix" tool (see "ahelp acis_run_hotpix"). See the "Use Observation-specific Bad Pixel Files" and "Identify ACIS Hot Pixels and Cosmic Ray Afterglows" threads for more information.

Example 1

unix% acis_set_ardlib bpix1.fits

This sets the ACIS bad pixel parameters to use bpix1.fits, for all the BADPIX<n> blocks in that file. The script will print out the settings of all the AXAF_ACIS<n>_BADPIX_FILE parameters and the location of the ardlib parameter file.

Example 2

unix% acis_set_ardlib ../bpix1.fits

This sets the ACIS bad pixel parameters to use ../bpix1.fits. Using the default parameter settings - namely absolutepath=yes - means that the file name will be changed to an absolute path before the parameter names are set.

Example 3

unix% acis_set_ardlib bpix1.fits verbose=0

This runs the script without producing any screen output.


name type ftype def min max reqd
badpixfile string input ""     yes
absolutepath boolean   yes      
ardlibfile string input ardlib      
verbose integer   0 0 5  

Detailed Parameter Descriptions

Parameter=badpixfile (string required filetype=input default="")

Bad pixel file for the observation.

This parameter is used to specify the name of the bad pixel file to use in the ardlib parameter file. It is searched for blocks that are called "BADPIX<n>", and the corresponding AXAF_ACIS<n>_BADPIX_FILE parameters in ardlib are set.

Parameter=absolutepath (boolean default=yes)

Use an absolute path in the parameter file.

Should the AXAF_ACIS<n>_BADPIX_FILE parameters use the absolute path to the bad pixel file? If set to yes then the current working directory is prepended to the badpixfile parameter, which is then cleaned up to remove all occurrences of "." and "..". If set to no then the badpixfile parameter is used.

The following table shows what the AXAF_ACIS0_BADPIX_FILE parameter would be set to when:

  • the current working directory is /data/chandra/work,
  • and the script is called with badpixfile set to "../obs/bpix1.fits", which contains a BADPIX0 block.

absolutepath parameter AXAF_ACIS0_BADPIX_FILE setting
yes /data/chandra/obs/bpix1.fits[BADPIX0]
no ../obs/bpix1.fits[BADPIX0]

Parameter=ardlibfile (string filetype=input default=ardlib)

Parameter file to change.

The name of the parameter file to change. This should be left as "ardlib" for most users.

Parameter=verbose (integer default=0 min=0 max=5)

Verbosity (0 for no screen output)

If set to 0 then the script will produce no screen output, other than parameter prompts, unless there is an error . When set to the default value of 1, the script will display the values of the AXAF_ACIS<n>_BADPIX_FILE parameters after it has set them. Values of 2 and higher provide debugging information.


The version scheme has changed to a date-based system and the screen output when verbose is above 1 has changed slightly. There should be no changes to the behavior of the tool.


This script is not an official part of the CIAO release but is made available as "contributed" software via the CIAO scripts page. Please see the installation instructions page for help on installing the package.


See the bugs page for this script on the CIAO website for an up-to-date listing of known bugs.

See Also

acis_bkgrnd_lookup, acis_fef_lookup, acisspec, add_grating_orders, add_grating_spectra, asphist, dither_region, dmarfadd, dmextract, eff2evt, fullgarf, hrc_bkgrnd_lookup, make_instmap_weights, merge_all, mkacisrmf, mkarf, mkexpmap, mkgarf, mkgrmf, mkinstmap, mkpsf, mkpsfmap, mkrmf, mkwarf, psextract, psf_project_ray, rmfimg, specextract

Last modified: June 2010